What does Runic Shield's debuff stack with?

As per this post, I know how other attack speed reduction items stack with each other. But where does Runic Shield fit into all of this. I would assume that, like the others, it only works with Midgardian, but does anyone have specifics?

Midgardian Mail and Enfeebling Curse stack with all other attack speed slows. Frostbound Hammer, Witchblade, and Runic Shield do not stack with each other but do stack with Midgardian Mail and Enfeebling Curse.

Frostbound Hammer and Witchblade have a particularly bad interaction where if you apply Frostbound Hammer to your target their attack speed slow will actually decrease 5% (so increasing their attack speed) since Frostbound Hammer's passive over-rules Witchblade's. This doesn't happen with Runic Shield.